This invention relates generally to a system for the continuous and uninterrupted treatment of a continuous metal web through a web feed station, a web entry storage station, an annealing station, a hot-dip coating station.
A known system for the continuous annealing of a continuous metal web includes an apparatus having a web feed end with web uncoilers, a web cleaning device, a web entry storage station, an annealing station and a web discharge storage station followed by a web discharge station with web recoilers. At the annealing station, the web is guided in the path of a loop via driven deflector rollers and is first heated to a maximum annealing temperature of 900.degree. C. This temperature is maintained for a predetermined period of time for the microstructure formation of the metal. Subsequently, the web is cooled down to ambient temperature in stages at the end of the annealing operation and emerges therefrom to enter the following web discharge storage or accumulator station. After the treated web has been moved through this station, it is subjected to an after-treatment, for example, by permitting it to pass through what is known as a skin-pass mill stand to effect a very light cold rolling. And, the after-treatment may include a stretch leveling device through which the treated strip passes before it is alternately wound into coils by a pair of recoilers.
Such a system for the continuous annealing of webs has a high output but is quite expensive, and only a limited number of qualified operators are available to operate the system to full capacity over long periods of time, i.e., several months running. However, the continuous operation of the plant without extended downtime is a requisite condition for its profitable utilization at the limit of its capacity. Also, for manufacturing purposes and for purposes of the production run, it is necessary that operation of such a costly system not be interrupted, since the frequent heating and cooling at the annealing station which occurs during such an interruption presents a drawback, since each start-up results in web rejection on a quality basis and results in start-up problems.
Another known system for the continuous annealing and hot-dip galvanizing of metal webs has an annealing station and a hot-dip galvanizing station downstream thereof in the direction of web movement. And, a web entry storage station is located upstream of the annealing station, and a web discharge storage station as well as a web after-treatment station are located downstream of the galvanizing station. Upstream of the web feed station uncoilers and a strip cleaning device are provided. At the discharge end, in addition to skin passing and stretcher leveling, the web is further subjected to after-treatment by chromate coating before the galvanized web is routed to the recoilers.
This system, also, only functions economically if it can be operated continuously for long periods of time without interruption. However, this is only made possible for operators of these expensive hot-dip galvanizing systems which must be operated at the limit of their capacity in order to optimize resource loading.
For those operators of hot-dip galvanizing systems who cannot optimize resource loading, it is necessary to shut down the system for a predetermined period from time to time. Thus, the repeated shut down and start-up of such a system is unprofitable and disadvantageous from a technical point of view. And, each new start-up of such a hot-dip galvanizing system leads to web rejection on a quality basis and to start-up problems.